Planetary transmissions having two interconnecting members and clutched input members

ABSTRACT

The family of transmissions has a plurality of members that can be utilized in powertrains to provide at least eight forward speed ratios and one reverse speed ratio. The transmission family members include three planetary gear sets having seven torque-transmitting mechanisms and two interconnecting members. The powertrain includes an engine that is selectively connectable to at least one of the planetary gear members and an output member that is continuously connected with another one of the planetary gear members. The seven torque-transmitting mechanisms provide interconnections between various gear members, the input shaft and the transmission housing, and are operated in combinations of two to establish at least eight forward speed ratios and at least one reverse speed ratio.

TECHNICAL FIELD

The present invention relates to a family of power transmissions havingthree planetary gear sets that are controlled by seventorque-transmitting devices to provide at least eight forward speedratios and at least one reverse speed ratio.

BACKGROUND OF THE INVENTION

Passenger vehicles include a powertrain that is comprised of an engine,multi-speed transmission, and a differential or final drive. Themulti-speed transmission increases the overall operating range of thevehicle by permitting the engine to operate through its torque range anumber of times. The number of forward speed ratios that are availablein the transmission determines the number of times the engine torquerange is repeated. Early automatic transmissions had two speed ranges.This severely limited the overall speed range of the vehicle andtherefore required a relatively large engine that could produce a widespeed and torque range. This resulted in the engine operating at aspecific fuel consumption point during cruising, other than the mostefficient point. Therefore, manually-shifted (countershafttransmissions) were the most popular.

With the advent of three- and four-speed automatic transmissions, theautomatic shifting (planetary gear) transmission increased in popularitywith the motoring public. These transmissions improved the operatingperformance and fuel economy of the vehicle. The increased number ofspeed ratios reduces the step size between ratios and therefore improvesthe shift quality of the transmission by making the ratio interchangessubstantially imperceptible to the operator under normal vehicleacceleration.

It has been suggested that the number of forward speed ratios beincreased to six or more. Six-speed transmissions are disclosed in U.S.Pat. No. 4,070,927 issued to Polak on Jan. 31, 1978; and U.S. Pat. No.6,422,969 issued to Raghavan and Usoro on Jul. 23, 2002.

Six-speed transmissions offer several advantages over four- andfive-speed transmissions, including improved vehicle acceleration andimproved fuel economy. While many trucks employ power transmissionshaving six or more forward speed ratios, passenger cars are stillmanufactured with three- and four-speed automatic transmissions andrelatively few five or six-speed devices due to the size and complexityof these transmissions.

Seven-speed transmissions are disclosed in U.S. Pat. No. 6,623,397issued to Raghavan, Bucknor and Usoro. Eight speed transmissions aredisclosed in U.S. Pat. No. 6,425,841 issued to Haka. The Hakatransmission utilizes three planetary gear sets and six torquetransmitting devices, including two brakes and two clutches, to provideeight forward speed ratios and a reverse speed ratio. One of theplanetary gear sets is positioned and operated to establish two fixedspeed input members for the remaining two planetary gear sets. Seven-,eight- and nine-speed transmissions provide further improvements inacceleration and fuel economy over six-speed transmissions. However,like the six-speed transmissions discussed above, the development ofseven-, eight- and nine-speed transmissions has been precluded becauseof complexity, size and cost.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improved familyof transmissions having three planetary gear sets controlled to provideat least eight forward speed ratios and at least one reverse speedratio.

In one aspect of the present invention, the family of transmissions hasthree planetary gear sets, each of which includes a first, second andthird member, which members may comprise a sun gear, a ring gear, or aplanet carrier assembly member, in any order.

In referring to the first, second and third gear sets in thisdescription and in the claims, these sets may be counted “first” to“third” in any order in the drawings (i.e., left to right, right toleft, etc.).

In another aspect of the present invention, the planetary gear sets maybe of the single pinion-type or of the double pinion-type.

In yet another aspect of the present invention, a first member of thefirst planetary gear set is continuously interconnected with a firstmember of the second planetary gear set and with a first member of thethird planetary gear set through a first interconnecting member.

In yet another aspect of the present invention, a second member of thefirst planetary gear set is continuously interconnected with a secondmember of the second planetary gear set and with a second member of thethird planetary gear set through a second interconnecting member.

The interconnecting members may be multi-piece rigid connections, singlepiece rigid connections, shared ring gears, shared carriers, shared sungears, long pinions, such as in a Ravigneax gear set, or other suitabledevices.

In yet a further aspect of the invention, each family memberincorporates an output shaft which is continuously connected with atleast one member of the planetary gear sets, and an input shaft which isnot continuously connected with any member of the planetary gear setsbut is selectively connectable with at least one member of the planetarygear sets through at least one of seven torque-transmitting mechanisms(torque transfer devices).

In still a further aspect of the invention, a first torque-transmittingmechanism, such as a clutch, selectively interconnects a member of thefirst or second planetary gear set with the input shaft.

In another aspect of the invention, a second torque-transmittingmechanism, such as a clutch, selectively interconnects another member ofthe second or third planetary gear set with the input shaft.

In a still further aspect of the invention, a third torque-transmittingmechanism, such as a clutch, selectively interconnects a member of thefirst or third planetary gear set with the input shaft.

In a still further aspect of the invention, a fourth torque-transmittingmechanism, such as a brake, selectively interconnects a member of thefirst or second planetary gear set with a stationary member(ground/transmission case).

In a still further aspect of the invention, a fifth torque-transmittingmechanism, such as a brake, selectively connects a member of the secondor third planetary gear set with the stationary member(ground/transmission case).

In still another aspect of the invention, a sixth torque-transmittingmechanism, such as a brake, selectively connects a member of the firstor third planetary gear set with the stationary member(ground/transmission case).

In still another aspect of the invention, a seventh torque-transmittingmechanism, such as a clutch, selectively interconnects a member of thefirst, second or third planetary gear set with another member of thefirst, second or third planetary gear set. Alternatively, the seventhtorque-transmitting mechanism, such as a brake, selectively connects amember of the first, second or third planetary gear set with thestationary member (ground/transmission case).

In still another aspect of the invention, the seven torque-transmittingmechanisms are selectively engageable in combinations of two to yield atleast eight forward speed ratios and at least one reverse speed ratio.

The above objects and other objects, features, and advantages of thepresent invention are readily apparent from the following detaileddescription of the best modes for carrying out the invention when takenin connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a is a schematic representation of a powertrain including aplanetary transmission incorporating a family member of the presentinvention;

FIG. 1 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 1 a;

FIG. 2 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 2 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 2 a;

FIG. 3 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 3 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 3 a;

FIG. 4 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 4 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 4 a;

FIG. 5 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 5 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 5 a;

FIG. 6 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 6 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 6 a;

FIG. 7 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 7 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 7 a;

FIG. 8 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 8 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 8 a;

FIG. 9 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 9 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 9 a;

FIG. 10 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention;

FIG. 10 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 10 a;

FIG. 11 a is a schematic representation of a powertrain having aplanetary transmission incorporating another family member of thepresent invention; and

FIG. 11 b is a truth table and chart depicting some of the operatingcharacteristics of the powertrain shown in FIG. 11 a.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings, wherein like characters represent the same orcorresponding parts throughout the several views, there is shown in FIG.1 a a powertrain 10 having a conventional engine 12, a planetarytransmission 14, and a conventional final drive mechanism 16.

The planetary transmission 14 includes an input shaft 17 connected withthe engine 12, a planetary gear arrangement 18, and an output shaft 19continuously connected with the final drive mechanism 16. The planetarygear arrangement 18 includes three planetary gear sets 20, 30 and 40.

The planetary gear set 20 includes a sun gear member 22, a ring gearmember 24, and a planet carrier assembly 26. The planet carrier assembly26 includes a plurality of pinion gears 27 rotatably mounted on acarrier member 29 and disposed in meshing relationship with both the sungear member 22 and the ring gear member 24.

The planetary gear set 30 includes a sun gear member 32, a ring gearmember 34, and a planet carrier assembly member 36. The planet carrierassembly member 36 includes a plurality of pinion gears 37 rotatablymounted on a carrier member 39 and disposed in meshing relationship withboth the sun gear member 32 and the ring gear member 34.

The planetary gear set 40 includes a sun gear member 42, a ring gearmember 44, and a planet carrier assembly member 46. The planet carrierassembly member 46 includes a plurality of pinion gears 47,48 rotatablymounted on a carrier member 49, wherein the pinion gears 47 are disposedin meshing relationship with the sun gear member 42 and the pinion gears48 disposed in meshing relationship with the ring gear member 44 andwith the pinion gears 47.

The planetary gear arrangement also includes seven torque-transmittingmechanisms 50, 52, 54, 56, 57, 58 and 59. The torque-transmittingmechanisms 50, 52, 54 and 56 are rotating-type torque-transmittingmechanisms, commonly termed clutches. The torque-transmitting mechanisms57, 58 and 59 are stationary-type torque transmitting mechanisms,commonly termed brakes or reaction clutches.

The input shaft 17 is not continuously connected with any planetary gearmember. The output shaft 19 is continuously connected with the ring gearmember 44. The carrier 26 is continuously connected with the ring gearmember 34 and with the sun gear member 42 through the interconnectingmember 70. The ring gear member 24 is continuously connected with theplanet carrier assembly members 36,46 through the interconnecting member72.

The planet carrier assembly member 26 is selectively connectable withthe input shaft 17 through the clutch 50. The planet carrier assemblymember 36 is selectively connectable with the input shaft 17 through theclutch 52. The sun gear member 22 is selectively connectable with theinput shaft 17 through the clutch 54. The sun gear member 32 isselectively connectable with the input shaft 17 through the clutch 56.The planet carrier assembly member 26 is selectively connectable withthe transmission housing 60 through the brake 57. The planet carrierassembly member 46 is selectively connectable with the transmissionhousing 60 through the brake 58. The sun gear member 22 is selectivelyconnectable with the transmission housing through the brake 59.

As shown in FIG. 1 b, and in particular the truth table disclosedtherein, the torque-transmitting mechanisms are selectively engaged incombinations of two to provide eight forward speed ratios and tworeverse speed ratios.

The reverse speed ratio is established with the engagement of the clutch56 and brake 58. The clutch 56 connects the sun gear member 32 with theinput shaft 17. The brake 58 connects the planet carrier assembly member46 with the transmission housing 60. The planet carrier assembly member26, ring gear member 34 and sun gear member 42 rotate at the same speed.The ring gear member 24 and planet carrier assembly members 36, 46 donot rotate. The sun gear member 32 rotates at the same speed as theinput shaft 17. The ring gear member 34 rotates as a speed determinedfrom the speed of the sun gear member 32 and the ring gear/sun geartooth ratio of the planetary gear set 30. The ring gear member 44rotates at the same speed as the output shaft 19. The ring gear member44, and therefore the output shaft 19, rotates at a speed determinedfrom the speed of the sun gear member 42 and the ring gear/sun geartooth ratio of the planetary gear set 40. The numerical value of thereverse speed ratio is determined utilizing the ring gear/sun gear toothratio of the planetary gear sets 30 and 40.

The extra reverse speed ratio (R′) is established with the engagement ofthe clutch 54 and the brake 57. The clutch 54 connects the sun gearmember 22 with the input shaft 17. The brake 57 connects the planetcarrier assembly member 26 with the transmission housing 60. The planetcarrier assembly member 26, ring gear member 34, and sun gear member 42do not rotate. The ring gear member 24 and planet carrier assemblymembers 36, 46 rotate at the same speed. The sun gear member 22 rotatesat the same speed as the input shaft 17. The ring gear member 24 rotatesat a speed determined from the speed of the sun gear member 22 and thering gear/sun gear tooth ratio of the planetary gear set 20. The ringgear member 44 rotates at the same speed as the output shaft 19. Thering gear member 44, and therefore the output shaft 19, rotates at aspeed determined from the speed of the planet carrier assembly member46, and the ring gear/sun gear tooth ratio of the planetary gear set 40.The numerical value of the extra reverse speed ratio (R′) is determinedutilizing the ring gear/sun gear tooth ratios of the planetary gear sets20 and 40.

The first forward speed ratio is established with the engagement of theclutch 54 and brake 59. The clutch 54 connects the sun gear member 22with the input shaft 17. The brake 59 connects the planet carrierassembly member 46 with the transmission housing 60. The ring gearmember 24 and planet carrier assembly members 36, 46 do not rotate. Theplanet carrier assembly member 26 rotates at the same speed as the ringgear member 34 and the sun gear member 42. The sun gear member 22rotates at the same speed as the input shaft 17. The planet carrierassembly member 26 rotates at a speed determined from the speed of thesun gear member 22 and the ring gear/sun gear tooth ratio of theplanetary gear set 20. The ring gear member 44 rotates at the same speedas the output shaft 19. The ring gear member 44, and therefore theoutput shaft 19, rotates at a speed determined from the speed of the sungear member 42 and the ring gear/sun gear tooth ratio of the planetarygear set 40. The numerical value of the first forward speed ratio isdetermined utilizing the ring gear/sun gear tooth ratios of theplanetary gear sets 20 and 40.

The second forward speed ratio is established with the engagement of theclutch 56 and the brake 57. The clutch 56 connects the sun gear member32 with the input shaft 17. The brake 57 connects the planet carrierassembly member 26 with the transmission housing 60. The planet carrierassembly member 26, ring gear member 34 and sun gear member 42 do notrotate. The ring gear member 24 rotates at the same speed as the planetcarrier assembly members 36, 46. The sun gear member 32 rotates at thesame speed as the input shaft 17. The planet carrier assembly member 36rotates at a speed determined from the speed of the sun gear member 32and the ring gear/sun gear tooth ratio of the planetary gear set 30. Thering gear member 44 rotates at the same speed as the output shaft 19.The ring gear member 44, and therefore the output shaft 19, rotates at aspeed determined from the speed of the planet carrier assembly member 46and the ring gear/sun gear tooth ratio of the planetary gear set 40. Thenumerical value of the second forward speed ratio is determinedutilizing the ring gear/sun gear tooth ratios of the planetary gear sets30 and 40.

The third forward speed ratio is established with the engagement of theclutch 50 and the brake 58. The clutch 50 connects the planet carrierassembly member 26 with input shaft 17. The brake 58 connects the planetcarrier assembly member 46 with the transmission housing 60. The planetcarrier assembly member 26, ring gear member 34 and sun gear member 42rotate at the same speed as the input shaft 17. The ring gear member 24and plant carrier assembly members 36, 46 do not rotate. The ring gearmember 44 rotates at the same speed as the output shaft 19. The ringgear member 44, and therefore the output shaft 19, rotates at a speeddetermined from the speed of the sun gear member 42 and the ringgear/sun gear tooth ratio of the planetary gear set 40. The numericalvalue of the third forward speed ratio is determined utilizing the ringgear/sun gear tooth ratio of the planetary gear set 40.

The fourth forward speed ratio is established with the engagement of theclutch 56 and brake 59. The clutch 56 connects the sun gear member 32with the input shaft 17. The brake 59 connects the sun gear member 22with the transmission housing 60. The sun gear member 22 does notrotate. The planet carrier assembly member 26 rotates at the same speedas the ring gear member 34 and the planet carrier assembly member 42.The ring gear member 24 rotates at the same speed as the planet carrierassembly members 36, 46. The speed of the planet carrier assembly member26 is determined from the speed of the ring gear member 24 and the ringgear/sun gear tooth ratio of the planetary gear set 20. The sun gearmember 32 rotates at the same speed as the input shaft 17. The planetcarrier assembly member 36 rotates at a speed determined from the speedof the ring gear member 34, the speed of the sun gear member 32, and thering gear/sun gear tooth ratio of the planetary gear set 30. The ringgear member 44 rotates at the same speed as the output shaft 19. Thering gear member 44, and therefore the output shaft 19, rotates at aspeed determined from the speed of the planet carrier assembly member46, the speed of the sun gear member 42, and the ring gear/sun geartooth ratio of the planetary gear set 40. The numerical value of thefourth forward speed ratio is determined utilizing the ring gear/sungear tooth ratios of the planetary gear sets 20, 30 and 40.

The fifth forward speed ratio is established with the engagement of theclutch 52 and the brake 57. The clutch 52 connects the planet carrierassembly member 36 with the input shaft 17. The brake 57 connects theplanet carrier assembly member 26 with the transmission housing 60. Theplanet carrier assembly member 26, ring gear member 34 and sun gearmember 42 do not rotate. The ring gear member 24, planet carrierassembly member 36 and planet carrier assembly member 46 rotate at thesame speed as the input shaft 17. The ring gear member 44 rotates at thesame speed as the output shaft 19. The ring gear member 44, andtherefore the output shaft 19, rotates at a speed determined from thespeed of the planet carrier assembly member 46 and the ring gear/sungear tooth ratio of the planetary gear set 40. The numerical value ofthe fifth forward speed ratio is determined utilizing the ring gear/sungear tooth ratio of the planetary gear set 40.

The sixth forward speed ratio is established with the engagement of theclutch 52 and the brake 59. The clutch 52 connects the planet carrierassembly member 36 with the input shaft 17. The brake 59 connects thesun gear member 22 with the transmission housing 60. The sun gear member22 does not rotate. The planet carrier assembly member 26 rotates at thesame speed as the ring gear member 34 and the sun gear member 42. Thering gear member 24 and planet carrier assembly members 36, 46 rotate atthe same speed as the input shaft 17. The planet carrier assembly member26 rotates at a speed determined from the speed of the ring gear member24 and the ring gear/sun gear tooth ratio of planetary gear set 20. Thering gear member 44 rotates at the same speed as the output shaft 19.The ring gear member 44, and therefore the output shaft 19, rotates at aspeed determined from the speed of the planet carrier assembly member46, the speed of the sun gear member 42, and the ring gear/sun geartooth ratio of planetary gear set 40. The numerical value of the sixthforward speed ratio is determined utilizing the ring gear/sun gear toothratios of the planetary gear sets 20 and 40.

The seventh forward speed ratio is established with the engagement ofthe clutches 50, 52. In this configuration, the input shaft 17 isdirectly connected to the output shaft 19. The numerical value of theseventh forward speed ratio is 1.

The eighth forward speed ratio is established with the engagement of theclutch 50 and the brake 59. The clutch 50 connects the planet carrierassembly member 26 with the input shaft 17. The brake 59 connects thesun gear member 22 with the transmission housing 60. The sun gear member22 does not rotate. The planet carrier assembly member 26, ring gearmember 34 and sun gear member 42 rotate at the same speed as the inputshaft 17. The ring gear member 24 and planet carrier assembly members36, 46, rotate at the same speed. The ring gear member 24 rotates at aspeed determined from the planetary carrier assembly member 26 and thering gear/sun gear tooth ratio of the planetary gear set 20. The ringgear member 44 rotates at the same speed as the output shaft 19. Thering gear member 44, and therefore the output shaft 19, rotates at aspeed determined from the speed of the planet carrier assembly member46, the speed of the sun gear member 42, and the ring gear/sun geartooth ratio of the planetary gear set 40. The numerical value of theeighth forward speed ratio is determined utilizing the ring gear/sungear tooth ratios of the planetary gear sets 20 and 40.

As set forth above, the engagement schedule for the torque-transmittingmechanisms is shown in the truth table of FIG. 1 b. This truth tablealso provides an example of speed ratios that are available utilizingthe ring gear/sun gear tooth ratios given by way of example in FIG. 1 b.The N_(R1)/N_(S1) value is the tooth ratio of the planetary gear set 20;the N_(R2)/N_(S2) value is the tooth ratio of the planetary gear set 30;and the N_(R3)/N_(S3) value is the tooth ratio of the planetary gear set40. Also, the chart of FIG. 1 b describes the ratio steps that areattained utilizing the sample of tooth ratios given. For example, thestep ratio between the first and second forward speed ratios is 2.43,while the step ratio between the reverse and first forward ratio is−0.44.

FIG. 2 a shows a powertrain 110 having a conventional engine 12, aplanetary transmission 114, and a conventional final drive mechanism 16.

The planetary transmission 114 includes an input shaft 17 continuouslyconnected with the engine 12, a planetary gear arrangement 118, and anoutput shaft 19 continuously connected with the final drive mechanism16. The planetary gear arrangement 118 includes three planetary gearsets 120, 130 and 140.

The planetary gear set 120 includes a sun gear member 122, a ring gearmember 124, and a planet carrier assembly 126. The planet carrierassembly 126 includes a plurality of pinion gears 127 rotatably mountedon a carrier member 129 and disposed in meshing relationship with boththe sun gear member 122 and the ring gear member 124.

The planetary gear set 130 includes a sun gear member 132, a ring gearmember 134, and a planet carrier assembly member 136. The planet carrierassembly member 136 includes a plurality of pinion gears 137,138rotatably mounted on a carrier member 139, wherein the pinion gears 137are disposed in meshing relationship with the sun gear member 132 andthe pinion gears 138 are disposed in meshing relationship with the ringgear member 134 and with the pinion gears 137.

The planetary gear set 140 includes a sun gear member 142, a ring gearmember 144, and a planet carrier assembly member 146. The planet carrierassembly member 146 includes a plurality of pinion gears 147 rotatablymounted on a carrier member 149 and disposed in meshing relationshipwith both the sun gear member 142 and the ring gear member 144.

The planetary gear arrangement 118 also includes seventorque-transmitting mechanisms 150, 152, 154, 156, 157, 158 and 159. Thetorque-transmitting mechanisms 150, 152 and 154 are rotating-typetorque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 156, 157, 158 and 159 are stationary-typetorque transmitting mechanisms, commonly termed brakes or reactionclutches.

The input shaft 17 is not continuously connected with any planetary gearmember. The output shaft 19 is continuously connected with the ring gearmember 144. The ring gear member 124 is continuously connected with thering gear member 134 and with the planet carrier assembly member 146through the interconnecting member 170. The planet carrier assemblymember 126 is continuously connected with the planet carrier assemblymember 136 and with the sun gear member 142 though the interconnectingmember 172.

The planet carrier assembly member 136 is selectively connectable withthe input shaft 17 through the clutch 150. The planet carrier assemblymember 146 is selectively connectable with the input shaft 17 throughthe clutch 152. The sun gear member 132 is selectively connectable withthe input shaft 17 through the clutch 154. The planet carrier assemblymember 126 is selectively connectable with the transmission housing 160through the brake 156. The ring gear member 134 is selectivelyconnectable with the transmission housing 160 through the brake 157. Thesun gear member 132 is selectively connectable with the transmissionhousing 160 through the brake 158. The sun gear member 122 isselectively connectable with the transmission housing 160 through thebrake 159.

The truth table of FIG. 2 b describes the engagement sequence utilizedto provide eight forward speed ratios and one reverse speed ratio in theplanetary gear arrangement 118 shown in FIG. 2 a, as well as an extrasecond forward speed ratio.

The truth tables given in FIGS. 2 b, 3 b, 4 b, 5 b, 6 b, 7 b, 8 b, 9 b,10 b and 11 b show the engagement sequences for the torque-transmittingmechanisms to provide at least eight forward speed ratios and at leastone reverse ratio. As shown and described above for the configuration inFIG. 1 a, those skilled in the art will understand from the respectivetruth tables how the speed ratios are established through the planetarygear sets identified in the written description.

As set forth above, the truth table of FIG. 2 b describes the engagementsequence of the torque-transmitting mechanisms utilized to provide thereverse drive ratio and eight forward speed ratios, as well as the extrasecond forward speed ratio. The truth table also provides an example ofthe ratios that can be attained with the family members shown in FIG. 2a utilizing the sample tooth ratios given in FIG. 2 b. The N_(R1)/N_(S1)value is the tooth ratio of the planetary gear set 120; theN_(R2)/N_(S2) value is the tooth ratio of the planetary gear set 130;and the N_(R3)/N_(S3) value is the tooth ratio of the planetary gear set140. Also shown in FIG. 2 b are the ratio steps between single stepratios in the forward direction as well as the reverse to first stepratio. For example, the first to second step ratio is 2.43.

Turning to FIG. 3 a, a powertrain 210 includes the engine 12, aplanetary transmission 214, and a final drive mechanism 16. Theplanetary transmission 214 includes an input shaft 17 continuouslyconnected with the engine 12, a planetary gear arrangement 218, and anoutput shaft 19 continuously connected with the final drive mechanism16. The planetary gear arrangement 218 includes three planetary gearsets 220, 230 and 240.

The planetary gear set 220 includes a sun gear member 222, a ring gearmember 224, and a planet carrier assembly 226. The planet carrierassembly 226 includes a plurality of pinion gears 227 rotatably mountedon a carrier member 229 and disposed in meshing relationship with boththe sun gear member 222 and the ring gear member 224.

The planetary gear set 230 includes a sun gear member 232, a ring gearmember 234, and a planet carrier assembly member 236. The planet carrierassembly member 236 includes a plurality of pinion gears 237 rotatablymounted on a carrier member 239 and disposed in meshing relationshipwith both the sun gear member 232 and the ring gear member 234.

The planetary gear set 240 includes a sun gear member 242, a ring gearmember 244, and a planet carrier assembly member 246. The planet carrierassembly member 246 includes a plurality of pinion gears 247, 248rotatably mounted on a carrier member 249, wherein the pinion gears 247are disposed in meshing relationship with the sun gear member 242 andthe pinion gears 248 are disposed in meshing relationship with the ringgear member 244 and with the pinion gears 247.

The planetary gear arrangement 218 also includes seventorque-transmitting mechanisms 250, 252, 254, 256, 257, 258 and 259. Thetorque-transmitting mechanisms 250, 252, and 254 are rotating typetorque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 256, 257, 258 and 259 are stationary-typetorque transmitting mechanism, commonly termed brake or reaction clutch.

The input shaft 17 is not continuously connected with any planetary gearmember. The output shaft 19 is continuously connected with the ring gearmember 244. The ring gear member 224 is continuous connected with theplanet carrier assembly member 236 and with the planet carrier assemblymember 246 through the interconnecting member 270. The planet carrierassembly member 226 is continuously connected with the sun gear member232 and sun gear member 242 through the interconnecting member 272.

The planet carrier assembly member 246 is selectively connectable withthe input shaft 17 through the clutch 250. The planet carrier assemblymember 226 is selectively connectable with the input shaft 17 throughthe clutch 252. The sun gear member 222 is selectively connectable withthe input shaft 17 through the clutch 254. The ring gear member 224 isselectively connectable with the transmission housing 260 through thebrake 256. The planet carrier assembly member 226 is selectivelyconnectable with the transmission housing 260 through the brake 257. Thesun gear member 222 is selectively connectable with the transmission 260through the brake 258. The ring gear member 234 is selective connectablewith the transmission housing 260 through the brake 259.

As shown in the truth table in FIG. 3 b, the torque-transmittingmechanisms are engaged in combinations of two to establish eight forwardspeed ratios and one reverse speed ratio, as well as an extra firstforward speed ratio.

As previously set forth, the truth table of FIG. 3 b describes thecombinations of engagements utilized for the forward and reverse speedratios. The truth table also provides an example of speed ratios thatare available with the family member described above. These examples ofspeed ratios are determined utilizing the tooth ratios given in FIG. 3b. The N_(R1)/N_(S1) value is the tooth ratio of the planetary gear set220; the N_(R2)/N_(S2) value is the tooth ratio of the planetary gearset 230; and the N_(R3)/N_(S3) value is the tooth ratio of the planetarygear set 240. Also depicted in FIG. 3 b is a chart representing theratio steps between adjacent forward speed ratios and between the firstand reverse speed ratio. For example, the first to second ratiointerchange has a step of 2.23.

A powertrain 310, shown in FIG. 4 a, includes the engine 12, a planetarytransmission 314, and the final drive mechanism 16. The planetarytransmission 314 includes an input shaft 17 continuously connected withthe engine 12, a planetary gear arrangement 318, and an output shaft 19continuously connected with the final drive mechanism 16. The planetarygear arrangement 318 includes three planetary gear sets 320, 330 and340.

The planetary gear set 320 includes a sun gear member 322, a ring gearmember 324, and a planet carrier assembly member 326. The planet carrierassembly member 326 includes a plurality of pinion gears 327 rotatablymounted on a carrier member 329 and disposed in meshing relationshipwith both the sun gear member 322 and the ring gear member 324.

The planetary gear set 330 includes a sun gear member 332, a ring gearmember 334, and a planet carrier assembly member 336. The planet carrierassembly member 336 includes a plurality of pinion gears 337, 338rotatably mounted on a carrier member 339 and disposed in meshingrelationship with each other, wherein the pinion gears 337 are engagedwith the sun gear member 332 and the pinion gears 338 are engaged withthe ring gear member 334.

The planetary gear set 340 includes a sun gear member 342, a ring gearmember 344, and a planet carrier assembly member 346. The planet carrierassembly member 346 includes a plurality of pinion gears 347 rotatablymounted on a carrier member 349 and disposed in meshing relationshipwith both the sun gear member 342 and the ring gear member 344.

The planetary gear arrangement 318 also includes seventorque-transmitting mechanisms 350, 352, 354, 356, 357, 358 and 359. Thetorque-transmitting mechanisms 350, 352, 354 and 356 are rotating typetorque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 357, 358 and 359 are stationary typetorque transfer devices commonly termed brakes or reaction clutches.

The input shaft 17 is not continuously connected with any planetary gearmember. The output shaft 19 is continuously connected with the ring gearmember 334. The planet carrier assembly member 326 is continuouslyconnected with the sun gear member 332 and with the planet carrierassembly member 346 through the interconnecting member 370. The sun gearmember 322 is continuously connected with the planet carrier assemblymember 336 and with the ring gear member 344 through the interconnectingmember 372.

The sun gear member 322 is selectively connectable with the input shaft17 through the clutch 350. The ring gear member 324 is selectivelyconnectable with the input shaft 17 through the clutch 352. The planetcarrier assembly member 346 is selectively connectable with the inputshaft 17 through the clutch 354. The sun gear member 342 is selectivelyconnectable with the input shaft 17 through the clutch 356. The ringgear member 344 is selectively connectable with the transmission housing360 through the brake 357. The planet carrier assembly member 346 isselectively connectable with the transmission housing 360 through thebrake 358. The sun gear member 342 is selectively connectable with thetransmission housing 360 through the brake 359.

The truth table shown in FIG. 4 b describes the engagement combinationand the engagement sequence necessary to provide two reverse driveratios and eight forward speed ratios. A sample of the numerical valuesfor the ratios is also provided in the truth table of FIG. 4 b. Thesevalues are determined utilizing the ring gear/sun gear tooth ratios alsogiven in FIG. 4 b. The N_(R1)/N_(S1) value is the tooth ratio for theplanetary gear set 320; the N_(R2)/N_(S2) value is the tooth ratio forthe planetary gear set 330; and the N_(R3)/N_(S3) value is the toothratio for the planetary gear set 340. Also given in FIG. 4 b is a chartdescribing the step ratios between the adjacent forward speed ratios andthe reverse to first forward speed ratio. For example, the first tosecond forward speed ratio step is 2.16.

A powertrain 410, shown in FIG. 5 a, includes the engine 12, a planetarytransmission 414 and the final drive mechanism 16. The planetarytransmission 414 includes a planetary gear arrangement 418, input shaft17 and output shaft 19. The planetary gear arrangement 418 includesthree simple planetary gear sets 420, 430 and 440.

The planetary gear set 420 includes a sun gear member 422, a ring gearmember 424, and a planet carrier assembly 426. The planet carrierassembly 426 includes a plurality of pinion gears 427 rotatably mountedon a carrier member 429 and disposed in meshing relationship with boththe sun gear member 422 and the ring gear member 424.

The planetary gear set 430 includes a sun gear member 432, a ring gearmember 434, and a planet carrier assembly member 436. The planet carrierassembly member 436 includes a plurality of pinion gears 437 rotatablymounted on a carrier member 439 and disposed in meshing relationshipwith both the ring gear member 434 and the sun gear member 432.

The planetary gear set 440 includes a sun gear member 442, a ring gearmember 444, and a planet carrier assembly member 446. The planet carrierassembly member 446 includes a plurality of pinion gears 447 rotatablymounted on a carrier member 449 and disposed in meshing relationshipwith both the sun gear member 442 and the ring gear member 444.

The planetary gear arrangement 418 also includes seventorque-transmitting mechanisms 450, 452, 454, 456, 457, 458 and 459. Thetorque-transmitting mechanisms 450, 452, 454 and 456 are rotating typetorque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 457, 458 and 459 are stationary-typetorque transmitting mechanisms, commonly termed brakes or reactionclutches.

The input shaft 17 is not continuously connected with any planetary gearmember. The output shaft 19 is continuously connected with the planetcarrier assembly member 446. The planet carrier assembly member 426 iscontinuously connected with the ring gear member 434 and the sun gearmember 442 through the interconnecting member 470. The ring gear member424 is continuously connected with the planet carrier assembly member436 and the ring gear member 444 through the interconnecting member 472.

The planet carrier assembly member 426 is selectively connectable withthe input shaft 17 through the clutch 450. The planet carrier assemblymember 436 is selectively connectable with the input shaft 17 throughthe clutch 452. The sun gear member 422 is selectively connectable withthe input shaft 17 through the clutch 454. The sun gear member 432 isselectively connectable with the input shaft 17 through the clutch 456.The planet carrier assembly member 426 is selectively connectable withthe transmission housing 460 through the brake 457. The planet carrierassembly member 436 is selectively connectable with the transmissionhousing 460 through the brake 458. The sun gear member 422 isselectively connectable with the transmission housing 460 through thebrake 459.

The truth table shown in FIG. 5 b describes the engagement combinationand sequence of the torque-transmitting mechanisms 450, 452, 454, 456,457, 458 and 459 that are employed to provide the forward and reversedrive ratios.

Also given in the truth table of FIG. 5 b is a set of numerical valuesthat are attainable with the present invention utilizing the ringgear/sun gear tooth ratios shown. The N_(R1)/N_(S1) value is the toothratio of the planetary gear set 420; the N_(R2)/N_(S2) value is thetooth ratio of the planetary gear set 430; and the N_(R3)/N_(S3) valueis the tooth ratio of the planetary gear set 440.

FIG. 5 b also provides a chart of the ratio steps between adjacentforward ratios and between the reverse and first forward ratio. Forexample, the ratio step between the first and second forward ratios is1.80.

A powertrain 510, shown in FIG. 6 a, includes an engine 12, a planetarygear transmission 514 and the final drive mechanism 16. The planetarytransmission 514 includes the input shaft 17, a planetary geararrangement 518 and the output shaft 19. The planetary gear arrangement518 includes three planetary gear sets 520, 530 and 540.

The planetary gear set 520 includes a sun gear member 522, a ring gearmember 524, and a planet carrier assembly 526. The planet carrierassembly 526 includes a plurality of pinion gears 527 rotatably mountedon a carrier member 529 and disposed in meshing relationship with boththe sun gear member 522 and the ring gear member 524.

The planetary gear set 530 includes a sun gear member 532, a ring gearmember 534, and a planet carrier assembly member 536. The planet carrierassembly member 536 includes a plurality of pinion gears 537 rotatablymounted on a carrier member 539 and disposed in meshing relationshipwith both the sun gear member 532 and the ring gear member 534.

The planetary gear set 540 includes a sun gear member 542, a ring gearmember 544, and a planet carrier assembly member 546. The planet carrierassembly member 546 includes a plurality of pinion gears 547 rotatablymounted on a carrier member 549 and disposed in meshing relationshipwith both the sun gear member 542 and the ring gear member 544.

The planetary gear arrangement 518 also includes seventorque-transmitting mechanisms 550, 552, 554, 556, 557, 558 and 559. Thetorque-transmitting mechanisms 550, 552, 554 and 556 are rotating typetorque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 557, 558 and 559 are stationary-typetorque transmitting mechanisms, commonly termed brakes or reactionclutches.

The input shaft 17 is not continuously connected with any planetary gearmember. The output shaft 19 is continuously connected with the planetcarrier assembly member 546. The planet carrier assembly member 526 iscontinuously connected with the ring gear member 534 and the ring gearmember 544 through the interconnecting member 570. The ring gear member524 is continuously connected with the planet carrier assembly member536 and sun gear member 542 through the interconnecting member 572.

The planet carrier assembly member 526 is selectively connectable withthe input shaft 17 through the clutch 550. The ring gear member 524 isselectively connectable with the input shaft 17 through the clutch 552.The sun gear member 522 is selectively connectable with the input shaft17 through the clutch 554. The sun gear member 532 is selectivelyconnectable with the input shaft 17 through the clutch 556. The planetcarrier assembly member 526 is selectively connectable with thetransmission housing 560 through the brake 557. The planet carrierassembly member 536 is selectively connectable with the transmissionhousing 560 through the brake 558. The sun gear member 522 isselectively connectable with the transmission housing 560 through thebrake 559.

The truth table shown in FIG. 6 b describes the engagement sequence andcombination of the torque-transmitting mechanisms to provide two reversespeed ratios and eight forward speed ratios. The chart of FIG. 6 bdescribes the ratio steps between adjacent forward speed ratios and theratio step between the reverse and first forward speed ratio.

The sample speed ratios given in the truth table are determinedutilizing the tooth ratio values also given in FIG. 6 b. TheN_(R1)/N_(S1) value is the tooth ratio of the planetary gear set 520;the N_(R2)/N_(S2) value is the tooth ratio of the planetary gear set530; and the N_(R3)/N_(S3) value is the tooth ratio of the planetarygear set 540.

A powertrain 610, shown in FIG. 7 a, has the engine 12, a planetarytransmission 614 and the final drive mechanism 16. The planetarytransmission 614 includes the input shaft 17, a planetary geararrangement 618 and the output shaft 19. The planetary gear arrangement618 includes three planetary gear sets 620, 630 and 640.

The planetary gear set 620 includes a sun gear member 622, a ring gearmember 624, and a planet carrier assembly 626. The planet carrierassembly 626 includes a plurality of pinion gears 627, 628 rotatablymounted on a carrier member 629 and disposed in meshing relationshipwith each other, wherein the pinion gears 627 are engaged with the sungear member 622 and the pinion gears 628 are engaged with the ring gearmember 624.

The planetary gear set 630 includes a sun gear member 632, a ring gearmember 634, and a planet carrier assembly member 636. The planet carrierassembly member 636 includes a plurality of pinion gears 637 rotatablymounted on a carrier member 639 and disposed in meshing relationshipwith both the sun gear member 632 and the ring gear member 634.

The planetary gear set 640 includes a sun gear member 642, a ring gearmember 644, and a planet carrier assembly member 646. The planet carrierassembly member 646 includes a plurality of pinion gears 647 rotatablymounted on a carrier member 649 and disposed in meshing relationshipwith both the sun gear member 642 and the ring gear member 644.

The planetary gear arrangement 618 also includes seventorque-transmitting mechanisms 650, 652, 654, 656, 657, 658 and 659. Thetorque-transmitting mechanisms 650, 652 and 654 are rotating typetorque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 656, 657, 658 and 659 are stationary-typetorque transmitting mechanisms, commonly termed brakes or reactionclutches.

The input shaft 17 is not continuously connected with any planetary gearmember. The output shaft 19 is continuously connected with the ring gearmember 634. The ring gear member 624 is continuously connected with theplanet carrier assembly member 636 and with the ring gear member 644through the interconnecting member 670. The planet carrier assemblymember 626 is continuously connected with the sun gear members 632 and642 through the interconnecting member 672.

The ring gear member 624 is selectively connectable with the input shaft17 through the clutch 650. The planet carrier assembly member 626 isselectively connectable with the input shaft 17 through the clutch 652.The sun gear member 622 is selectively connectable with the input shaft17 through the clutch 654. The ring gear member 644 is selectivelyconnectable with the transmission housing 660 through the brake 656. Thesun gear member 642 is selectively connectable with the transmissionhousing 660 through the brake 657. The sun gear member 622 isselectively connectable with the transmission housing 660 through thebrake 658. The planet carrier assembly member 646 is selectivelyconnectable with the transmission housing 660 through the brake 659.

The truth table shown in FIG. 7 b describes the combination oftorque-transmitting mechanism engagements that will provide two reversedrive ratios and eight forward speed ratios, as well as the sequence ofthese engagements and interchanges.

The ratio values given are by way of example and are establishedutilizing the ring gear/sun gear tooth ratios given in FIG. 7 b. Forexample, the N_(R1)/N_(S1) value is the tooth ratio of the planetarygear set 620; the N_(R2)/N_(S2) value is the tooth ratio of theplanetary gear set 630; and the N_(R3)/N_(S3) value is the tooth ratioof the planetary gear set 640. The ratio steps between adjacent forwardratios and the reverse to first ratio are also given in FIG. 7 b.

A powertrain 710, shown in FIG. 8 a, has the conventional engine 12, aplanetary transmission 714, and the conventional final drive mechanism16. The engine 12 is drivingly connected with the planetary transmission714 through the input shaft 17. The planetary transmission 714 isdrivingly connected with the final drive mechanism 16 through the outputshaft 19. The planetary transmission 714 includes a planetary geararrangement 718 that has a first planetary gear set 720, a secondplanetary gear set 730, and a third planetary gear set 740.

The planetary gear set 720 includes a sun gear member 722, a ring gearmember 724, and a planet carrier assembly 726. The planet carrierassembly 726 includes a plurality of pinion gears 727, 728 rotatablymounted on a carrier member 729 and meshingly engaged with each other.The pinion gears 727 are disposed in meshing relationship with the sungear member 722 and the pinion gears 728 are disposed in meshingrelationship with the ring gear member 724.

The planetary gear set 730 includes a sun gear member 732, a ring gearmember 734, and a planet carrier assembly member 736. The planet carrierassembly member 736 includes a plurality of pinion gears 737 rotatablymounted on a carrier member 739 and disposed in meshing relationshipwith both the sun gear member 732 and the ring gear member 734.

The planetary gear set 740 includes a sun gear member 742, a ring gearmember 744, and a planet carrier assembly member 746. The planet carrierassembly member 746 includes a plurality of pinion gears 747, 748rotatably mounted on a carrier member 749 and meshingly engaged witheach other. The pinion gears 747 are engaged with the sun gear member742 and the pinion gears 748 are engaged with the ring gear member 744.The planetary gear arrangement 718 also includes seventorque-transmitting mechanisms 750, 752, 754, 756, 757, 758 and 759. Thetorque-transmitting mechanisms 750, 752, 754 and 756 are rotating typetorque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 757, 758 and 759 are stationary-typetorque transmitting mechanisms, commonly termed brakes or reactionclutches.

The input shaft 17 is not continuously connected with any planetary gearmember. The output shaft 19 is continuously connected with the ring gearmember 744. The ring gear member 724 is continuously connected with thering gear member 734 and the with planet carrier assembly member 746through the interconnecting member 770. The planet carrier assemblymember 726 is continuously connected with planet carrier assembly member736 and with the sun gear member 742 through the interconnecting member772.

The planet carrier assembly member 746 is selectively connectable withthe input shaft 17 through the clutch 750. The planet carrier assemblymember 726 is selectively connectable with the input shaft 17 throughthe clutch 752. The sun gear member 722 is selectively connectable withthe input shaft 17 through the clutch 754. The sun gear member 732 isselectively connectable with the input shaft 17 through the clutch 756.The ring gear member 724 is selectively connectable with thetransmission housing 760 through the brake 757. The planet carrierassembly member 726 is selectively connectable with the transmissionhousing 760 through the brake 758. The sun gear member 722 isselectively connectable with the transmission housing 760 through thebrake 759.

The truth table of FIG. 8 b defines the torque-transmitting mechanismengagement sequence utilized for each of the forward and reverse speedratios. Also given in the truth table is a set of numerical values thatare attainable with the present invention utilizing the ring gear/sungear tooth ratios given in FIG. 8 b. The N_(R1)/N_(S1) value is thetooth ratio of the planetary gear set 720; the N_(R2)/N_(S2) value isthe tooth ratio of the planetary gear set 730; and the N_(R3)/N_(S3)value is the tooth ratio of the planetary gear set 740.

FIG. 8 b also provides a chart of the ratio steps between adjacentforward ratios and between the reverse and first forward ratio. Forexample, the ratio step between the first and second forward ratios is1.74.

A powertrain 810, shown in FIG. 9 a, has the conventional engine 12, aplanetary transmission 814, and the final drive mechanism 16. The engine12 is drivingly connected with the planetary transmission 814 throughthe input shaft 17. The planetary transmission 814 is drivinglyconnected with the final drive mechanism 16 through the output shaft 19.The planetary transmission 814 includes a planetary gear arrangement 818that has a first planetary gear set 820, a second planetary gear set830, and a third planetary gear set 840.

The planetary gear set 820 includes a sun gear member 822, a ring gearmember 824, and a planet carrier assembly 826. The planet carrierassembly 826 includes a plurality of pinion gears 827, 828 rotatablymounted on a carrier member 829 and disposed in meshing relationshipwith each other. The pinion gears 828 are engaged with the sun gearmember 822, and the pinion gears 827 are engaged with the ring gearmember 824.

The planetary gear set 830 includes a sun gear member 832, a ring gearmember 834, and a planet carrier assembly member 836. The planet carrierassembly member 836 includes a plurality of pinion gears 837 rotatablymounted on a carrier member 839 and disposed in meshing relationshipwith both the sun gear member 832 and the ring gear member 834.

The planetary gear set 840 includes a sun gear member 842, a ring gearmember 844, and a planet carrier assembly member 846. The planet carrierassembly member 846 includes a plurality of pinion gears 847, 848rotatably mounted on a carrier member 849 and disposed in meshingrelationship with each other. The pinion gears 848 are engaged with thering gear member 844, and the pinion gears 847 are engaged with the sungear member 842. The planetary gear arrangement 818 also includes seventorque-transmitting mechanisms 850, 852, 854, 856, 857, 858 and 859. Thetorque-transmitting mechanisms 850, 852, 854 and 856 are rotating typetorque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 857, 858 and 859 are stationary-typetorque transmitting mechanisms, commonly termed brakes or reactionclutches.

The input shaft 17 is not continuously connected with any planetary gearmember. The output shaft 19 is continuously connected with the ring gearmember 844. The ring gear member 824 is continuously connected with theplanet carrier assembly members 836 and 846 through the interconnectingmember 870. The planet carrier assembly member 826 is continuouslyconnected with the sun gear members 832 and 842 through theinterconnecting member 872.

The planet carrier assembly member 826 is selectively connectable withthe input shaft 17 through the clutch 850. The planet carrier assemblymember 836 is selectively connectable with the input shaft 17 throughthe clutch 852. The ring gear member 834 is selectively connectable withthe input shaft 17 through the clutch 854. The sun gear member 822 isselectively connectable with the input shaft 17 through the clutch 856.The planet carrier assembly member 826 is selectively connectable withthe transmission housing 860 through the brake 857. The planet carrierassembly member 846 is selectively connectable with the transmissionhousing 860 through the brake 858. The sun gear member 822 isselectively connectable with the transmission housing 860 through thebrake 859.

The truth table shown in FIG. 9 b defines the torque-transmittingmechanism engagement sequence that provides two reverse speed ratios andeight forward speed ratios shown in the truth table and available withthe planetary gear arrangement 818. A sample of numerical values for theindividual ratios is also given in the truth table of FIG. 9 b. Thesenumerical values have been calculated using the ring gear/sun gear toothratios also given by way of example in FIG. 9 b. The N_(R1)/N_(S1) valueis the tooth ratio of the planetary gear set 820; the N_(R2)/N_(S2)value is the tooth ratio of the planetary gear set 830; and theN_(R3)/N_(S3) value is the tooth ratio of the planetary gear set 840.FIG. 9 b also describes the ratio steps between adjacent forward ratiosand between the reverse and first forward ratio.

The powertrain 910, shown in FIG. 10 a, includes the conventional engine12, a planetary transmission 914, and the conventional final drivemechanism 16. The engine 12 is drivingly connected with the planetarytransmission 914 through the input shaft 17. The planetary transmission914 is drivingly connected with the final drive mechanism 16 through theoutput shaft 19. The planetary transmission 914 includes a planetarygear arrangement 918 that has a first planetary gear set 920, a secondplanetary gear set 930, and a third planetary gear set 940.

The planetary gear set 920 includes a sun gear member 922, a ring gearmember 924, and a planet carrier assembly 926. The planet carrierassembly 926 includes a plurality of pinion gears 927, 928 that arerotatably mounted on a carrier member 929 and disposed in meshingrelationship with each other. The pinion gears 927 are engaged with thesun gear member 922, and the pinion gears 928 are engaged with the ringgear member 924.

The planetary gear set 930 includes a sun gear member 932, a ring gearmember 934, and a planet carrier assembly member 936. The planet carrierassembly member 936 includes a plurality of pinion gears 937 rotatablymounted on a carrier member 939 and disposed in meshing relationshipwith both the ring gear member 934 and the sun gear member 932.

The planetary gear set 940 includes a sun gear member 942, a ring gearmember 944, and a planet carrier assembly member 946. The planet carrierassembly member 946 includes a plurality of pinion gears 947 rotatablymounted on a carrier member 949 and disposed in meshing relationshipwith both the sun gear member 942 and the ring gear member 944.

The planetary gear arrangement 918 also includes seventorque-transmitting mechanisms 950, 952, 954, 956, 957, 958 and 959. Thetorque-transmitting mechanisms 950, 952 and 954 are rotating-typetorque-transmitting mechanisms, commonly termed clutches. Thetorque-transmitting mechanisms 956, 957, 958 and 959 are stationary-typetorque-transmitting mechanisms, commonly termed brakes or reactionclutches.

The input shaft 17 is not continuously connected with any planetary gearmember. The output shaft 19 is continuously connected with the planetcarrier assembly member 946. The ring gear member 924 is continuouslyconnected with the ring gear member 934 and with the sun gear member 942through the interconnecting member 970. The planet carrier assemblymember 926 is selectively connectable with the planet carrier assemblymember 936 and with the ring gear member 944 through the interconnectingmember 972.

The planet carrier assembly member 926 is selectively connectable withthe input shaft 17 through the clutch 950. The sun gear member 922 isselectively connectable with the input shaft 17 through the clutch 952.The sun gear member 932 is selectively connectable with the input shaft17 through the clutch 954. The ring gear member 924 is selectivelyconnectable with the transmission housing 960 through the brake 956. Theplanet carrier assembly member 926 is selectively connectable with thetransmission housing 960 through the brake 957. The sun gear member 922is selectively connectable with the transmission housing 960 through thebrake 958. The sun gear member 932 is selectively connectable with thetransmission housing 960 through the brake 959.

The truth table of FIG. 10 b describes the torque-transmitting mechanismengagement sequence utilized to provide two reverse speed ratios andeight forward speed ratios. The truth table also provides a set ofexamples for the ratios for each of the reverse and forward speedratios. These numerical values have been determined utilizing the ringgear/sun gear tooth ratios given in FIG. 10 b. The N_(R1)/N_(S1) valueis the tooth ratio of the planetary gear set 920; the N_(R2)/N_(S2)value is the tooth ratio of the planetary gear set 930; and theN_(R3)/N_(S3) value is the tooth ratio of the planetary gear set 940.

A powertrain 1010, shown in FIG. 11 a, includes the conventional engine12, a planetary transmission 1014, and the conventional final drivemechanism 16. The engine is drivingly connected with the planetarytransmission 1014 through the input shaft 17. The planetary transmission1014 is drivingly connected with the final drive mechanism 16 throughthe output shaft 19. The planetary transmission 1014 includes aplanetary gear arrangement 1018 that has a first planetary gear set1020, a second planetary gear set 1030, and a third planetary gear set1040.

The planetary gear set 1020 includes a sun gear member 1022, a ring gearmember 1024, and a planet carrier assembly 1026. The planet carrierassembly 1026 includes a plurality of pinion gears 1027 rotatablymounted on a carrier member 1029 and disposed in meshing relationshipwith both the sun gear member 1022 and the ring gear member 1024.

The planetary gear set 1030 includes a sun gear member 1032, a ring gearmember 1034, and a planet carrier assembly member 1036. The planetcarrier assembly member 1036 includes a plurality of pinion gears 1037rotatably mounted on a carrier member 1039 and disposed in meshingrelationship with both the ring gear member 1034 and the sun gear member1032.

The planetary gear set 1040 includes a sun gear member 1042, a ring gearmember 1044, and a planet carrier assembly member 1046. The planetcarrier assembly member 1046 includes a plurality of pinion gears 1047,1048 rotatably mounted on a carrier member 1049 and disposed in meshingrelationship with each other. The pinion gears 1048 are engaged with thering gear member 1044 and the pinion gears 1047 are engaged with the sungear member 1042. The planetary gear arrangement 1018 also includesseven torque-transmitting mechanisms 1050, 1052, 1054, 1056, 1057, 1058and 1059. The torque-transmitting mechanisms 1050, 1052, 1054 and 1056are rotating-type torque-transmitting mechanisms, commonly termedclutches. The torque-transmitting mechanisms 1057, 1058 and 1059 arestationary-type torque-transmitting mechanisms, commonly termed brakesor reaction clutches.

The input shaft 17 is not continuously connected with any planetary gearmember. The output shaft 19 is continuously connected with the ring gearmember 1044. The planet carrier assembly member 1026 is continuouslyconnected with the ring gear member 1034 and with sun gear member 1042through the interconnecting member 1070. The ring gear member 1024 iscontinuously connected with the planet carrier assembly members 1036 and1046 through the interconnecting member 1072. The ring gear member 1024is selectively connectable with the input shaft 17 through the clutch1050. The planet carrier assembly member 1026 is selectively connectablewith the input shaft 17 through the clutch 1052. The sun gear member1022 is selectively connectable with the input shaft 17 through theclutch 1054. The sun gear member 1032 is selectively connectable withthe input shaft 17 through the clutch 1056. The planet carrier assemblymember 1046 is selectively connectable with the transmission housing1060 through the brake 1057. The sun gear member 1022 is selectivelyconnectable with the transmission housing 1060 through the brake 1058.The sun gear member 1032 is selectively connectable with thetransmission housing 1060 through the brake 1059.

The truth table shown in FIG. 11 b describes the engagement combinationsand the engagement sequence necessary to provide the reverse drive ratioand nine forward speed ratios. A sample of the numerical values for theratios is also provided in the truth table of FIG. 11 b. These valuesare determined utilizing the ring gear/sun gear tooth ratios also givenin FIG. 11 b. The N_(R1)/N_(S1) value is the tooth ratio for theplanetary gear set 1020; the N₂/N_(S2) value is the tooth ratio for theplanetary gear set 1030; and the N_(R3)/N_(S3) value is the tooth ratiofor the planetary gear set 1040. Also given in FIG. 11 b is a chartdescribing the step ratios between the adjacent forward speed ratios andthe reverse to first forward speed ratio.

While the best modes for carrying out the invention have been describedin detail, those familiar with the art to which this invention relateswill recognize various alternative designs and embodiments forpracticing the invention within the scope of the appended claims.

1. A multi-speed transmission comprising: an input shaft; an outputshaft; first, second and third planetary gear sets each having first,second and third members; said output shaft being continuouslyinterconnected with a member of said planetary gear sets, and said inputshaft not being continuously interconnected with any member of saidplanetary gear sets; a first interconnecting member continuouslyinterconnecting said first member of said first planetary gear set withsaid first member of said second planetary gear set and said firstmember of said third planetary gear set; a second interconnecting membercontinuously interconnecting said second member of said first planetarygear set with said second member of said second planetary gear set andsecond member of said third planetary gear set; a firsttorque-transmitting mechanism selectively interconnecting a member ofsaid first or second planetary gear set with said input shaft; a secondtorque-transmitting mechanism selectively interconnecting a member ofsaid second or third planetary gear set with said input shaft; a thirdtorque-transmitting mechanism selectively interconnecting a member ofsaid first or third planetary gear set with said input shaft; a fourthtorque-transmitting mechanism selectively interconnecting a member ofsaid first or second planetary gear set with a stationary member; afifth torque-transmitting mechanism selectively interconnecting a memberof said second or third planetary gear set with said stationary member;a sixth torque-transmitting mechanism selectively interconnecting amember of said first or third planetary gear set with said stationarymember; and a seventh torque-transmitting mechanism selectivelyinterconnecting a member of said first, second or third planetary gearset with another member of said first, second or third planetary gearset, or with said stationary member; said torque-transmitting mechanismsbeing engaged in combinations of two to establish at least eight forwardspeed ratios and at least one reverse speed ratio between said inputshaft and said output shaft.
 2. The transmission defined in claim 1,wherein said first, second and third torque-transmitting mechanismscomprise clutches, and said fourth, fifth, sixth and seventhtorque-transmitting mechanisms comprise brakes.
 3. The transmissiondefined in claim 1, wherein said first, second, third and seventhtorque-transmitting mechanisms comprise clutches, and said fourth,fifth, and sixth torque-transmitting mechanisms comprise brakes.
 4. Thetransmission defined in claim 1, wherein planet carrier assembly membersof each of said planetary gear sets are single-pinion carriers.
 5. Thetransmission defined in claim 1, wherein at least one planet carrierassembly member of said planetary gear sets is a double-pinion carrier.6. The transmission defined in claim 1, wherein two planet carrierassembly members of said planetary gear sets are double-pinion carriers.7. A multi-speed transmission comprising: an input shaft; an outputshaft; a planetary gear arrangement having first, second and thirdplanetary gear sets, each planetary gear set having first, second andthird members; said output shaft being continuously interconnected witha member of said planetary gear sets, and said input shaft not beingcontinuously interconnected with any member of said planetary gear sets;a first interconnecting member continuously interconnecting said firstmember of said first planetary gear set with said first member of saidsecond planetary gear set and said first member of said third planetarygear set; a second interconnecting member continuously interconnectingsaid second member of said first planetary gear set with said secondmember of said second planetary gear set and second member of said thirdplanetary gear set; and seven torque-transmitting mechanisms forselectively interconnecting said members of said planetary gear setswith said input shaft, with a stationary member or with other members ofsaid planetary gear sets, said seven torque-transmitting mechanismsbeing engaged in combinations of two to establish at least eight forwardspeed ratios and at least one reverse speed ratio between said inputshaft and said output shaft.
 8. The transmission defined in claim 7,wherein a first of said seven torque-transmitting mechanisms is operablefor selectively interconnecting a member of said first or secondplanetary gear set with said input shaft.
 9. The transmission defined inclaim 7, wherein a second of said seven torque-transmitting mechanismsis operable for selectively interconnecting a member of said second orthird planetary gear set with said input shaft.
 10. The transmissiondefined in claim 7, wherein a third of said seven torque-transmittingmechanisms is selectively operable for interconnecting a member of saidfirst or third planetary gear set with said input shaft.
 11. Thetransmission defined in claim 7, wherein a fourth of said seventorque-transmitting mechanisms is selectively operable forinterconnecting a member of said first or second planetary gear set withsaid stationary member.
 12. The transmission defined in claim 7, whereina fifth of said seven torque-transmitting mechanisms is selectivelyoperable for interconnecting a member of said second or third planetarygear set with said stationary member.
 13. The transmission defined inclaim 7, wherein a sixth of said seven torque-transmitting mechanismsselectively interconnects a member of said first or third planetary gearset with said stationary member.
 14. The transmission defined in claim7, wherein a seventh of said seven torque-transmitting mechanismsselectively interconnects a member of said first, second or thirdplanetary gear set with another member of said first, second or thirdplanetary gear set, or with said stationary member.
 15. The transmissiondefined in claim 7, wherein planet carrier assembly members of each ofsaid planetary gear sets are single-pinion carriers.
 16. Thetransmission defined in claim 7, wherein at least one planet carrierassembly member of said planetary gear sets is a double-pinion carrier.